Hydrogen storage development

I just read my latest "Material Matters" issue from Sigma Aldrich. One story relates to the storage/production of hydrogen using liquid "fuels". These fuels contain easily oxidized structures that release hydrogen upon the application of modest heat in the presence of an active catalyst. A working prototype exists and the storage numbers look impressive.

The volume required to store 10 kg of H2 is on par with liquid hydrogen and about half that of metal hydride storage systems. The fuel is not seriously air or water reactive and is about as energetic as standard gasoline fuel. The fuel is stored at 1 atm. The weight of the hydrogen storage system (again for 10 kg H2) is comparable with compressed hydrogen (at 350 bar) and again about half that of the metal hydrides.

Cost is also about half that of metal hydrides and since it is a liquid of low vapor pressure, existing infrastructure can be easily adapted to transport, store and dispense the stuff. The cost for hydrogen in this form is $2.50 per equivalent gallon of gas energy. Not too bad.

The chemistry is probably related to the organothiol/organodisulfide chemistry. The patent application mentions methyl thiol, butanethiol, 1,4-butanedithiol and 1,4-cyclohexanedithiol. The latter example produces 4 moles of H2 per mole of fuel when oxidized all the way to 1,4-dithioparabenzoquinone.

Staff: Mentor

This is an excellent idea -- a "reusable liquid fuel" that has roughly the same energy capacity as gasoline, but with an "ash" that can be simply recharged with hydrogen and sold again.

I'm all for it! (How bad does it smell?)

- Warren

You can find it at the Sigma Aldrich Website. I have a hardcopy of the Material Matters "Hydrogen Storage Materials", 2007, Vol 2, No. 2, pg 23-25.
It may take some effort to navigate through the site...

It does sound good. There is always a catch though. Let me guess...the catalyst is made out of Fabergé eggs or something extremely toxic. I'm a cynic. I am crossing my fingers though.

It is probably nanosized gold particles.

Edit:
This from the Claims of the patent

2. The method of claim 1, wherein the metal substrate comprises a metal selected from the group consisting of gold, silver, platinum, copper, and mercury.

The real question is the stability of the byproduct 1,4-dithioparabenzoquinone. All those double bonds are going to want to polymerize since the structure contains 2 more electrons than is required for aromaticity. These things could string end to end forming an insoluble polysulfide polymer, fouling the catalyst. I am interested to hear how long the catalyst remains reactive and how much material is lost after each recharge cycle.

The cost for hydrogen in this form is $2.50 per equivalent gallon of gas energy. Not too bad.

Waaaaait a minute. Is that just the cost of transporting the Hydrogen using this "fuel"? Or does that include the actual production of the hydrogen in the first place? I would expect that the vast majority of the cost will be the cost of the actual energy that is stored in the form of free Hydrogen sitting around to begin with.

I mention it because I've found to my annoyance that most Hydrogen enthusiasts seem unaware of the basic fact that Hydrogen is not an "energy source", it is an "energy storage mechanism". You still have to actually get the energy somewhere, such as by burning oil, or solar power, or deuterium in giant tokamaks

They suggest using N-ethylcarbazole (see page 5 of above presentation) as the liquid carrier. This liquid is stored in the vehicle until ready for use. It is then passed through a catalyst along with the use of waste heat from the fuel cell (or hydrogen IC engine) to release the hydrogen. The liquid, less hydrogen, is returned to a secondary reservoir. The idea is to take this liquid out of the waste tank on the vehicle when refueling, and refill the fuel tank.

Regarding cost for H2, right now the cost is of course dependant on how much hydrogen a consumer will be purchasing, but for a typical experimental hydrogen refueling site, the going cost for hydrogen is on the order of $10 per diesel gallon equivalent. That cost can vary significantly depending on a variety of factors, and can easily pass $20 per diesel gallon equivalent. I've seen numbers as low as about $3 per diesel gallon equivalent, but I believe those numbers are heavily subsidized and not representative of actual cost.

Waaaaait a minute. Is that just the cost of transporting the Hydrogen using this "fuel"? Or does that include the actual production of the hydrogen in the first place?

The $2.50 per kg of H2 (energy equivalent to 1 gal of gasoline) includes the cost of hydrogen generated by steam methane reforming at $1.20 per Kg. Hydrogen generation costs (and sources) will always be a concern for hydrogen based energy storage. The real advantage of the hydrogen based energy applied to private transportation is in the switch from petroleum-based energy (ie. foriegn dependence) to the domestic supplies of energy sources be they coal, natural gas, algae, solar, etc...

The $2.50 per kg of H2 (energy equivalent to 1 gal of gasoline) includes the cost of hydrogen generated by steam methane reforming at $1.20 per Kg. Hydrogen generation costs (and sources) will always be a concern for hydrogen based energy storage. The real advantage of the hydrogen based energy applied to private transportation is in the switch from petroleum-based energy (ie. foriegn dependence) to the domestic supplies of energy sources be they coal, natural gas, algae, solar, etc...

Are you saying you get the energy from methane? Based on your line of reasoning, how is using hydrogen that stores methane energy better than just burning the methane? There are plenty of natural gas powered vehicles out there. It seems to be a more mature technology than hydrogen.

Based on your line of reasoning, how is using hydrogen that stores methane energy better than just burning the methane?

I don't know what you mean by "...using hydrogen that stores methane energy..." but I can guess at what you are trying to say... First, I'd like to point out that my 'line of reasoning' doesn't mention that burning hydrogen is 'better' than burning anything else except foriegn sources of petroleum. Second, and this wasn't in any of my posts, using hydrogen to power an electric vehicle is somewhat more efficient than using an internal combustion engine with hydrocarbon fuel. NOx, sulfate aerosols, CO, CO2, methane, are not produced at the point of use (usually near a city) and so hydrogen also has the advantage of preventing the emission of these pollutants near heavily populated areas. I don't buy into the claims that anthropogenic global warming is largely caused by the CO2 or methane emmisions (greenhouse gasses) but many do and these 'pollutants' have to be considered. Methane is a very potent catalyst for ozone formation... that much is well established.

I don't get anything from hydrogen or methane. The AUTHORS calculated the cost of hydrogen storage using hydrogen from steam methane reforming which is currently the cheapest source of hydrogen.

I was using the universal "you", since the pronoun "one" has become obsolete in conversational English. And I was wondering about the source of the energy, not the source of the hydrogen. Am I correct in understanding that the energy comes from the methane?

I don't know what you mean by "...using hydrogen that stores methane energy..." but I can guess at what you are trying to say... First, I'd like to point out that my 'line of reasoning' doesn't mention that burning hydrogen is 'better' than burning anything else except foriegn sources of petroleum.

Please stop being pedantic. I don't care about having some stupid argument or playing any ridiculous "I'm smarter than you" game, I just want some information about a field I obviously know very little about. If you don't feel like having a normal conversation about it with someone who doesn't have your academic credentials, say the word and I'll happily quit this thread and save you further irritation.

Are you saying that you actually do feel natural gas powered vehicles are better than hydrogen vehicles in this respect? I didn't assume that was your position, since it would seem surprising for you to be a big hydrogen supporter if it competes with a technology you perceive as better overall. But if that is your position, then fine, this line of questioning is complete as far as I am concerned.

Second, and this wasn't in any of my posts, using hydrogen to power an electric vehicle is somewhat more efficient than using an internal combustion engine with hydrocarbon fuel.

More efficient in what respect? Are you saying that from the original methane required to the amount of kinetic energy delivered to a vehicle, better energy efficiency is obtained if hydrogen is used as an intermediate than if the methane is burned directly?

I don't buy into the claims that anthropogenic global warming is largely caused by the CO2 or methane emmisions (greenhouse gasses) but many do and these 'pollutants' have to be considered.

If I am to assume that you feel that hydrogen powered vehicles reduce CO2 emissions, may I ask why? Is it just the aforementioned efficiency thing? Or are you just saying that emitting CO2 further away from municipalities is somehow better from the perspective of those who do disagree with your position WRT global warming? And if so, why?

Please don't confuse my willingness to discuss an advancement in hydrogen storage technology with that of advocacy of using hydrogen over any other fuel, including methane or natural gas.

I see your point regarding methane energy being saved in the form of hydrogen. Currently methane reforming to produce hydrogen is the cheapest hydrogen. That is the only reason that I mentioned methane. In the future perhaps excess nuclear electrical generating capacity can be adapted to produce hydrogen or solar panels or algae or biomass can be used to produce hydrogen... I don't know. These are methods that are being discussed as potential hydrogen sources. They each have their strengths and weaknesses.

The efficiency of hydrogen powered fuel cells to power a vehicle is much higher than that of the internal combustion engine. This from the Online Fuel Cell Information Resource: (http://www.fuelcells.org/basics/benefits.html [Broken])

"High Efficiency. Because they make energy electrochemically, and do not burn fuel, fuel cells are fundamentally more efficient than combustion systems. When the fuel cell is sited near the point of use, its waste heat can be captured for beneficial purposes (cogeneration). In large-scale building systems, these fuel cell cogeneration systems can reduce facility energy service costs by 20% to 40% compared to conventional energy service.

Fuel cell power generation systems in operation today achieve 40% to 50% fuel-to-electricity efficiency utilizing hydrocarbon fuels.
Systems fueled by hydrogen can consistently provide more than 50 percent efficiency. Even more efficient systems are under development.
In combination with a turbine, electrical efficiencies can exceed 60 percent.
When waste heat is put to use for heating and cooling, fuel utilization can exceed 85 percent.
Fuel cell passenger vehicles are expected to be up to three times more efficient than internal combustion engines, which now operate at 10 to 16 percent efficiency."

One of the major hurdles for hydrogen is the lack of an infrastructure to distribute it as liquid H2, borohydrides, high or low pressure gas and so forth. Natural gas powered vehicles are everywhere and the technology is certainly much further along than that of hydrogen but they don't sell well because of the lack of a distribution infrastructure. This development could be adapted to use existing infrastructure... that's an important advantage.

LNG powered vehicles deserve consideration. Perhaps you should start a new thread to discuss it. Here is a leading reference...